That is the warning that lingers from the broadside delivered by Bob Corker (Tenn.) during his Twitter war with Trump. Most Americans already take for granted much of what the Republican senator said — that the president peddles falsehoods online and has to be corralled by the "adults" around him. But the notion offered by the silver-haired, sober-minded chairman of the Foreign Relations Committee that Trump might launch a catastrophic war invites sleepless nights even for those who have already resigned themselves to four years of domestic chaos.

There would seem to be plenty to worry about, from Trump's insistently hawkish statements about North Korea, including personal insults directed at ruler Kim Jong Un, to his showy announcement of "decertification" of the Iran nuclear deal Friday. Yet as Corker sees it, the biggest problem is that Trump is neutering his own chief diplomat, Secretary of State Rex Tillerson, and thereby inviting "binary" situations in which the United States will have to choose between war and a North Korea or Iran capable of threatening the United States with nuclear weapons.

"You cannot publicly castrate your own secretary of state without giving yourself that binary choice," Corker told me in a phone interview Friday. "The tweets — yes, you raise tension in the region [and] it's very irresponsible. But it's the first part" — the "castration" of Tillerson — "that I am most exercised about."

Tillerson gets low marks from many in Washington, both inside and outside the State Department, who think he has cooperated with Trump's attempt to strip U.S. diplomacy of resources, authority and public profile. But as Corker sees it, Tillerson has been instrumental in opening a path away from confrontation with North Korea through quiet diplomacy with China.

"The greatest diplomatic activities we have are with China, and the most important, and they have come a long, long way," Corker said. "Some of the things we are talking about are phenomenal."

The problem, he suggested, is Trump's tweets and other statements implying that there is no deal to be made with North Korea and that Tillerson "is wasting his time," as one tweet put it. Such comments are causing the Chinese to back away from what has been an incipient willingness to bring serious pressure to bear on Pyongyang.

"When you jack the legs out from under your chief diplomat, you cause all that to fall apart," Corker said. "Us working with [Beijing] effectively is the key to not getting to a binary choice. When you publicly castrate your secretary of state, you take that off the table."

Corker has a somewhat analogous view of Trump's actions on Iran, which explains why he is trying to answer the president's demand for legislation placing new conditions on the nuclear deal. In tune with Trump, Corker is proposing that Congress amend a bill it passed in 2015 that provides for U.S. sanctions on Iran to be reimposed if Iran does not comply with the deal. Under the revision, the sanctions would "snap back" if Iran did not meet new conditions, such as allowing more intrusive international inspections and giving up a sunset clause that removes restrictions on some nuclear activities, including uranium enrichment, beginning eight years from now.

Corker acknowledged that the initiative could be taken as a U.S. attempt to unilaterally revise a multinational agreement. But he said his intention was not to destroy but to "freeze" the nuclear pact. "We're not going to do anything that violates the JCPOA," he said, referring to the deal by its initials.

Once again, Corker said his intent is to preserve a diplomatic option Trump is threatening to shred; the president said Friday that the deal "will be terminated" if Congress does not act. Corker said Congress can preserve the deal and lay the groundwork for more negotiations with allies and Iran. "This is a way to begin the conversation," he said. That dialogue is likely to be difficult: Congressional Democrats and European governments are reacting negatively to Trump's demands.

In context, Corker's assertion that "we could be heading towards World War III" was a more pungent way of conveying Trump's undermining of diplomacy. Trump "isn't necessarily a warmonger," he told the New York Times. The point was that the combination of exaggerated statements and the undercutting of Tillerson could corner the White House.

Corker may also have had a more sly purpose. "Now that the [World War III suggestion] is out there, [Trump] will do everything in his power to prove that it is not true," he told me. If so, the senator from Tennessee will have achieved his purpose.